1.Field of the Invention
This invention relates to photographic processes for providing an imagewise distribution of a reagent, such as photographically active reagent or a dye and particularly to processes for the formation of color images and to photographic products useful therein.
2. Description of the Prior Art
Diffusion transfer photographic processes are now well-known. In preparing silver images according to such processes, an exposed photosensitive element comprising a light-sensitive silver halide emulsion is developed by treating the emulsion with a processing composition comprising an aqueous alkaline solution of a silver halide developing agent and a silver halide solvent. The developable silver halide of the emulsion is reduced to image silver by the developing agent while the silver halide solvent forms an imagewise distribution of a soluble silver complex with the undeveloped silver halide. This imagewise distribution of soluble silver complex is, at least in part, transferred by imbibition to a superposed image-receiving layer where it is reduced to form a silver transfer image.
It has been proposed in U.S. Pat. No. 3,443,941 of Howard G. Rogers to utilize certain principles of the silver diffusion transfer art in the formation of color images. In particular, it has been proposed to utilize the properties of the imagewise distribution of silver ions in the soluble silver complex to control imagewise transfer of a color-providing substance to a suitable receiving stratum to provide a color image thereon.
Included among the color-providing materials disclosed as useful in such a system are (A) normally diffusible color-providing materials that are rendered non-diffusible upon reaction with silver ions and/or a soluble silver complex containing the same and (B) normally non-diffusible color-providing materials that are rendered diffusible upon reaction with silver ions and/or a soluble silver complex containing the same. Such color-providing materials include complete dyes or dye intermediates which form a complete dye upon subsequent reaction.
It is known that various chemical reactions are assisted by silver ion including reactions involving cleavage of a compound into one or more fragments. One example of a cleavage reaction that is assisted by silver ion is the silver ion-accelerated hydrolysis of mono thio analogs of tetrahydropyranyl ethers as disclosed in U.S. Pat. No. 3,068,099. Other examples of such reactions are the silver ion-accelerated cleavage of disulfides and of thioesters as discussed by L. F. Lindoy, Coordin. Chem. Rev., 4 (1969), 41-71 and the silver ion-accelerated elimination of mercaptan in the preparation of carbodiimides, isocyanates and isothiocyanates as discussed by A. F. Ferris et al., J. Org. Chem., 28, 71-74 (1968). Further examples of such reactions are the selective removal of certain S-protecting groups from cysteines using silver ion as discussed by L. Zervas et al., J. Am. Chem. Soc., 84, 3887-3891 (1962) and the silver ion-accelerated hydrolysis of silyl acetylenic compounds as reported in Rec. trav. chim. des Pays-Bas 86, 1138 (1967).
Besides the above reactions, it is also known that heavy metal ions, particularly mercuric and silver ions, accelerate cleavage of certain cyclic and linear 1,3-sulfur-nitrogen compounds, i.e., compounds having a sulfur atom and a nitrogen atom, each linked by a single bond to a common carbon atom. Such compounds undergo cleavage in a stepwise fashion between the S atom and the C atom common to the S and N atoms and also between the N atom and the common C atom. As discussed in The Chemistry of Penicillins, National Academy of Sciences, Washington, D. C., pages 926 and 927, the cleavage of thiazolidines by mercury salts has become standard practice in the inactivation of penicillin compounds. It is also mentioned in this reference that certain thiazolidine compounds undergo cleavage in the presence of silver ion. The cleavage of benzothiazolines accelerated by the presence of various metal ions including silver ion is reported in the aforementioned Lindoy reference, while the cleavage of certain linear compounds containing the sulfur-carbon-nitrogen configuration assisted by mercuric and silver ions is reported by T. Yamaguichi et al., Bulletin of the Chemical Society of Japan, 40, 1952-1954 (1967).
Though certain thiazolidine compounds have been used in photographic processes, for example, to improve ratios of speed to fog as described in U.S. Pat. 3,565,625, such compounds have not been used in a photographic system to provide an imagewise distribution of a reagent.